Diaphragm for telephone-recervers



(No Model.)

N. BOWLING.

DIAPHRAGM FOR TELEPHONEIREGEIVERS. No. 337,753. Patented Mar. 9, 1886.

WITN ESSES V yr/in/ M m magnet.

UNITED STATES PATENT OFFICE.

NORTH DOWLING, OF PHILADELPHIA, PENNSYLVANIA.

DIAPHRAGM FOR :I'ELEPHONE-RECEIVERS'.

- SPECIFICATION forming part 0! Letters Patent No. 337,753, dated March 9. 1886.

Application filed Fehruaryl4,1885. Serial No. 155,911. (No model.) i

To all whom it may concern:

Be it known that I, NoRTH DOWLING, a citizen of the United States, residing at the city and county of Philadelphia and State of Pennsylvania, have invented certain newand use ful Improvements in Diaphragms for 'IelephOneReceiVers, of which the followingis a full, clear, and exact description, reference being had to the accompanying drawings.

The object of my invention is to provide an improved diaphragm or armature plate for electrical telephonereceivers. I attain this object by means of a compound plate in which are combined a substance-such as ironadapted to be attracted by the usual magnets of telephone-receivers, and materialsuch as vulcanized rubber-possessing a high vibratory or resonant quality.

What I believe to be the best mode of carrying out my invention is as follows, reference being had to the annexed illustrations, of which Figure 1 is an exterior or face view of the plate. Fig. 2 is a section in a plane at right angles to the minor axis, and Figs. 3 and 4 are views corresponding, respectively, to Figs. 1 and 2 of a modification of the invention. 4

I take a foraminous disk, preferably of fine iron wire cloth a=say,'No. 28 wire and one sixty-fourth inch mesli-which constitutes the metallic plate armature of the usual receiver- This iron cloth disk I embed within a body of vulcanized rubber, b, by first sulficient-l'y heating a sheet or sheets of the latter in order to soften it, and then compressing the wires together until the meshes of the wirecloth are filled up. and an integrally solid plate ,of about the thickness of the telephonereceiver diaphragms in general use is produced. The plate is mounted in the usual manner. A like result is attained by combining with the hard rubber iron in comminu'ted form-such as filings a, Fig. 4-the latter be ing embedded in the rubber b in any suitable manner.

In lieu of hard rubber, there may be employed shellac, celluloid, chorolithion, orot-her suitable vibratory or resonant substance in which the iron in foraminated or comminuted form may beelnbedded or combined so as to constitute a practically solid or integral vibratory plate, hard rubber, however, being preferred.

I have demonstrated by practical experiment that a telephonic-receiver diaphragm 5 5 constructed as hereinbefore described .produces better results than the iron plates in vogue, the sounds and articulations being reproduced rounder and clearer and without the quavering'metallic quality given out by the usual sheet-iron or lei-retype plates. In other words, my improved diaphragm ha's'a greater ability to reproduce or give out all forms of vibratory motion than any with which I am acquainted. v

I may state that with the use of the present invention in connection with certain other improvements in telephonic receivers and in transmitters (for which I shall file applications for patents simultaneously herewith) conver- 7o sations have been carried on. in an ordinary whisper over actual lines between points sev-. eral miles apart andwith perfect clearness in ordinary tones with the speakers at a distance of twenty feet and more from the transmitter, every vocal wave being distinctly reproduced to the ear at the receiver.

Having thus described my invention I claim as new and desireto secure by Letters ment-- 1. A diaphragm for telephone receivers composed of a body of iron embedded in a body of resonant material, substantially as specified.

2. A diaphragm for telephone receivers, consisting of a body of comminuted iron em- 8 bedded in a body of hard rubber, snbslantiall y as specified.

In testimony whereof I haveherennto aflixed my signature this 17th day of January, A. D. 1885. v NORTH BOWLING.

\Vitnesscs:

J OHN NOLAN, FRANCIS S. BROWN. 

